Cory Gardner, and the limits of the personhood attack

Republican Corey Gardner, right, makes a point as Democratic opponent Mark Udall listens during their debate for the U.S. Senate at Memorial Hall on Oct. 9, 2014 in Pueblo, Colo. (AP Photo/The Pueblo Chieftain, Chris McLean)

For much of the summer, even Republicans were acknowledging that Sen. Mark Udall's (D-Colo.) attacks on Rep. Cory Gardner's (R-Colo.) past support for so-called "personhood" legislation had hamstrung Gardner's nascent campaign.

Of course, it wasn't always that way. Between May and early September, Gardner's numbers in most polls were either middling or underwater (higher unfavorable rating than favorable one). And that's not exactly where you want to be just as you are introducing yourself to a statewide audience.

And then there's the fact that Gardner has pretty firmly changed his position on personhood -- an evolution that, while politically convenient, could serve to diminish the effectiveness of the personhood strategy.

Udall's image, meanwhile, has taken a turn for the worse, according to the polls. The CNN poll shows him at 45 percent favorable and 51 percent unfavorable, and SurveyUSA earlier this week showed his job approval at 36 percent, vs. 53 percent disapproval -- negative 17-point spread. In contrast, SurveyUSA just last month showed Udall in positive territory.

The CNN poll has Gardner up four points, and the newer SurveyUSA poll somehow had him up only two, despite Udall's cratering image. Both are within the margin of error.

The horse-race numbers aside, though, if the image numbers in these polls are accurate, Udall is going to have a pretty tough time winning reelection come Nov. 4. And if he fails to, there will be plenty of chatter about the role personhood did or didn't play.

That's not to say the personhood attacks don't work -- they did (for a while) and can -- but they're probably more a supplement than an overarching strategy.